Which algorithms, between ant colony or classical routing algorithms, have a better time complexity for the shortest path problem?
No. In general, you can't find a tight bound for evolutionary algorithms, and it is one of the main difference of these algorithms with the classical algorithms. 

You should notice that it does not mean you can't find when the evolutionary algorithms are finished! But, you can't find a tight bound for the algorithms time complexity to reach to the optimal solution or how much that solution is near to the optimal solution (in contrast to the approximation algorithms).